Hey guys, i have a few questions that have to do with 4wd on my l6 4.2 wrangler. I've had it for about 2.5 years, constantly replacing this and that, as it goes for many. I've finally got it running well, at least the best it has since i've owned it, so i wanted to move on to fixing the 4wd.

What i believe is called the "actuator", connected to the front axle on the passenger side, has a missing male piece where the vacuum hose would fit over to engage. Thats the first obvious weak point in the system. My question is, after replacing that piece, if it still wont engage, are there any other common problems i should keep an eye out for?

Second question is, will engaging 4wd amplify any imperfections in the engine or drive shaft? Like i said, i've been fixing it as i go and have it running pretty good, but its not new. I live in Ohio, and were having a very mild winter like many other states, and if fixing it at this point could cause DD problems i'd rather hold off. I've replaced the four U-joints along the drive shaft, but would any potential week spots be under a considerably larger amount of pressure?

Last, and i could probably find this answer somewhere... But would a locking system bypass a lot of potential troubles? With my tax return coming in soon i wouldnt mind spending the money on a kit if it would save a lot of hassle in the long run.

You won't (or shouldn't ) be using 4WD on pavement. It is only for use off road or in slick (think snow) conditions. So normal on road running will be unaffected if you return the system to factory operating condition.

But, a popular option is to either permanently engage the inner and outer shaft, or replace both with a one piece axle shaft. You still only use 4WD off road, but the front driveshaft will now spin all the time.

Fishnic, thats a good idea. I might do that and at least see if thats all that is wrong with it.

My question regarding the drive shaft/axle may have been hard to understand. I was just wondering if, since the 4wd has never been engaged the whole time i've owned it, could there be any dormant issues that engaging 4wd would bring to light?

Also, thanks for the advise Old4x. You helped me out a lot on my last thread from the upgraded icm to a carb rebuild. I'll look into the axle options you mentioned.

My jeep sat in a parking lot for 4 years then in my warehouse for 3 years before I ever turned a wrench on it. The inside of the actuator was pristine - as compared to the outside which one nipple had rusted off. Do yourself a huge favor and start pb blasting the 4 bolts on it a few times a day for at least 3-4 days before you plan on breaking her down.

The inside is splashed with the gear oil inside the axle, so unless water or moisture was introduced, it should look real nice and slide real easy.

If you want to test it to see if the actuator goes back and forth:

1. Jack up the passenger side tire off the ground - it should spin freely.
2. remove all the vacuum hoses from the actuator.
3. depending which nipple is rusted off - hook a small length of vacuum hose up to one of the nipples. if it is hooked up on the closest one to the passenger side -blow lightly into it. if it is hooked to the middle nipple - suck lightly into it. it does not take alot of pressure to move the fork inside. 3 seconds worth should move it. then try and spin the tire. if the fork moved it will lock the drivers side and passenger side axle together and the tire will not spin freely anymore

Thanks, that actuator test is just what i was hoping to find how to do. Makes since now that you explain what to do.

I'm not going to tackle this until saturday since it needs to get me to work for the rest of the week. Ill start pb blasting tomorrow.

Couple more questions though. Am i correct in stating the nipple closest to pass is disengage, middle is engage, and the one closest to driver's side is indicating light? I just looked over a diagram, and thats the impression i got. I cant remember now, and its too dark and wet out to check right now, but i'm thinking it was the nip closest to the driver's side that was missing. I'f i dont need the indicator light can i just skip this?

Lastly, do you remember what drill/tap size you used? I read your thread and you never mentioned. Are threaded nipples something autozone or a hardware store commonly carries? (never been in the market for a threaded nipple)

IMO its not worth trying to fix the actuator, as it is a terrible system to begin with. I would permanently lock it in 4x4 and disconnect / plug the vacuum lines. Its as simple as taking off the actuator, removing an E-clip, sliding the fork over, and re-installing the clip. Worst thing that can happen is your front drive shaft isn't balanced, so you can spend a couple bucks getting it balanced and have worry free operation of your 4x4 after that.

I had to repair my actuator twice, both times when I really needed it (Read: Heavy snow, cold, awful conditions). The second time I said screw it and permanently locked it in, and luckily my driveshaft is balanced enough to not cause vibes. That was 3 years ago and I've never once had a problem using 4WD since.

IMO its not worth trying to fix the actuator, as it is a terrible system to begin with. I would permanently lock it in 4x4 and disconnect / plug the vacuum lines. Its as simple as taking off the actuator, removing an E-clip, sliding the fork over, and re-installing the clip. Worst thing that can happen is your front drive shaft isn't balanced, so you can spend a couple bucks getting it balanced and have worry free operation of your 4x4 after that.

I had to repair my actuator twice, both times when I really needed it (Read: Heavy snow, cold, awful conditions). The second time I said screw it and permanently locked it in, and luckily my driveshaft is balanced enough to not cause vibes. That was 3 years ago and I've never once had a problem using 4WD since.

Looks like this when done. I keep an extra one around for demonstration purposes.

Thanks, that actuator test is just what i was hoping to find how to do. Makes since now that you explain what to do.

I'm not going to tackle this until saturday since it needs to get me to work for the rest of the week. Ill start pb blasting tomorrow.

Couple more questions though. Am i correct in stating the nipple closest to pass is disengage, middle is engage, and the one closest to driver's side is indicating light? I just looked over a diagram, and thats the impression i got. I cant remember now, and its too dark and wet out to check right now, but i'm thinking it was the nip closest to the driver's side that was missing. I'f i dont need the indicator light can i just skip this?

Lastly, do you remember what drill/tap size you used? I read your thread and you never mentioned. Are threaded nipples something autozone or a hardware store commonly carries? (never been in the market for a threaded nipple)

Thanks a lot, great info.

You are correct on the nipple configuration. If its only the one closest to the drivers side then that is the indicator light. Plug it with your finger and see if the actuator slides over.

You will be able to feel the vacuum with your fingers on each hose when the shift lever is in the correct position. its not a heck of alot - mine gauges out at about 24lbs.

I will get you the size I tapped tomorrow, have it at work. It all depends on the size of hole you have to start with.

The brass barb i used looks similar to below, but i bought it a little too small - the hose wasnt tight enough. I alley mechanic'd a fix by winding electrical tape around it a few times and now i have a good seal.

That may be your only problem. The middle nipple pulls the actuator towards the drivers side locking the 2 axles together. The vacuum from the middle nipple flows through the third nipple to the 4x4 indicator. if the third one is rusted off and open, you have a vacuum leak at that point and probably do not have enough suction to slide the fork over. try plugging it and seeing if you get enough suction then.

That was my thinking! Now that you backed me on it, i'm thinking this could actually be a QUICK fix to my yj, which comes around not very often.

I'll update if i get a chance to look at it today, gotta get to work soon so i'm not sure if i'll have the time.

Thanks a bunch. I'll let ya know what i find out.

BTW Thanks for the pic up there Anticanman. I missed that before.

Edit: I just ran out to check, and as i said its still very wet out so i didnt want to get under it in my work clothes. But i can tell the middle nipple looks good, the driver's side nip is gone. I do not know the condition of the nip pointing to pass side tire, but i am happy to report the one that i know is broken is indeed just the indicator light.

Fishnic, i read in your thread, and other's have suggested locking 4wd in 100%. Is this called permi-lock, as apposed to posi-lock? I'm not sure what the diff is. What happens when you lock it in 100%? Does that mean 4wd will always be engaged? I was under the impression 4wd on dry pavement is bad for it. (Not to mention gas mileage)

If everything will hook up as-is, that would be great. I'm just trying to better understand all my options here.